#include<functional>
#include<vector>
using namespace std;
namespace bit
{
    template <class T, class Container = vector<T>, class Compare = less<T> >
    class priority_queue
    {
    private:
        Container c;
        Compare comp;
        void adjustup(int child) {
            int parent = (child - 1) / 2;
            while (child > 0) {
                if (comp(c[parent], c[child])) {
                    swap(c[parent], c[child]);
                    child = parent;
                    parent = (child - 1) / 2;
                }
                else break;
            }
        }
        void adjustdown(int parent) {
            int child = parent * 2 + 1;
            while (child < c.size()) {
                if (child + 1 < c.size() && comp(c[child], c[child + 1])) {
                    child++;
                }
                if (comp(c[parent], c[child])) {
                    swap(c[parent], c[child]);
                    parent = child;
                    child = parent * 2 + 1;
                }
                else break;
            }

        }
    public:
        priority_queue() {
        }
        template <class InputIterator>
        priority_queue(InputIterator first, InputIterator last) {
            while (first < last) {
                c.push_back(*first);
                first++;
            }
            for (int i = (c.size() - 2) / 2; i >= 0; i--) {
                adjustdown(i);
            }
        }

        bool empty() const {
            return c.empty();
        }
        size_t size() const {
            return c.size();
        }
        T& top()const{
            return c[0];
        }
        void push(const T& x) {
            c.push_back(x);
            adjustup(c.size() - 1);
        }
        void pop() {
            swap(c[0], c[c.size() - 1]);
            c.pop_back();
            adjustdown(0);
        }

    };
}